1. Field of the Invention
The invention relates to a receiving apparatus of a digital satellite broadcast which is used in a receiving and recording/reproducing system of a digital satellite broadcast such that a signal in which video data and audio data are broadcast by a transport stream of an MPEG (Moving Picture Experts Group) 2 system is received and the transport stream is recorded/reproduced to/from a recording medium such as digital video tape, optical disk, magnetic disk, or the like. The invention also relates to a processing method of the reproduced transport stream.
2. Description of the Related Art
In recent years, the spread of IEEE1394 has been started as a digital interface to transfer video data and audio data between digital video equipment and digital audio equipment at a high speed. In IEEE1394, an isochronous transfer mode and an asynchronous transfer mode are supported. In the isochronous transfer mode, a delay time of transmission is guaranteed and it is suitable for use in high speed transfer of a time-sequential data stream such as video data or audio data. In the asynchronous transfer mode, it is guaranteed to certainly transmit data to a node of a partner destination and it is suitable for use in the case of certainly transfer data such as a command or the like.
In recent years, the spread of digital satellite broadcasting has been started. In the digital satellite broadcast, digital video data and audio data are compressed and packetized and transmitted by the transport stream of the MPEG2 system. A packet identifier called a PID is provided in a header of a transmission packet. Video packets and audio packets of a plurality of programs are multiplexed to the same stream and transmitted.
When such a digital satellite broadcast is received, a decoder for receiving the digital satellite broadcast called an IRD (Integrated Receiver Decoder) is connected to a television receiver. A signal of the digital satellite broadcast received by a parabolic antenna is supplied to the IRD. In the IRD, the transport stream of MPEG2 is demodulated, a video packet and an audio packet of a desired program are extracted from the transport stream of MPEG2 by the PID, and a video signal and an audio signal are decoded from the video packet and audio packet. The video signal and audio signal are supplied from the IRD to the television receiver.
To receive such a digital satellite broadcast, a construction such that the digital interface of IEEE1394 is provided for the IRD has been proposed. If the digital interface of IEEE1394 is provided for the IRD, the IRD and equipment such as a recording/reproducing apparatus or the like are connected and a receiving and recording/reproducing system of the digital satellite broadcast can be constructed. If such a system is constructed, the transport stream of MPEG2 transmitted by the digital satellite broadcast can be recorded/reproduced as it is.
That is, upon recording, the transport stream of MPEG2 received on the IRD side is sent to the recording/reproducing equipment through the digital interface of IEEE1394. The transport stream of MPEG2 is recorded as it is onto a recording medium by the recording/reproducing equipment. Upon reproduction, the transport stream of MPEG2 is reproduced from the recording medium. The reproduced transport stream of MPEG2 is transmitted to the IRD through the digital interface of IEEE1394. The transport stream of MPEG2 is decoded by the IRD.
As mentioned above, if the digital interface of IEEE1394 is provided for the IRD and the IRD and the recording/reproducing equipment are connected and the receiving and recording/reproducing system of the digital satellite broadcast is constructed, the transport stream of MPEG2 transmitted by the digital satellite broadcast can be recorded/reproduced as it is to/from a recording medium such as digital video tape, optical disk, magnetic disk, or the like.
In the digital satellite broadcast, packets of a plurality of programs have been multiplexed to the same carrier frequency and transmitted. Two systems may be considered, in the case where the transport stream of MPEG2 transmitted by the digital satellite broadcast is recorded/reproduced to/from the recording medium such as a tape cassette or the like as mentioned above. One is a single program recording system in which the video packet and audio packet of one desired program are extracted on the IRD side and sent to the digital recording/reproducing equipment and recorded. The other is a multiprogram recording system in which the video packets and audio packets of a plurality of programs transmitted by one carrier frequency are sent from the IRD to the digital recording/reproducing apparatus and recorded as they are.
The multiprogram recording system has an advantage in that a plurality of programs can be simultaneously recorded. Upon reproduction, however, processes for selecting a desired program from the packets of a plurality of programs and extracting the video packet and audio packet of the program are necessary, the user may become confused, and the processes are complicated. A program of the digital satellite broadcast is scrambled on the basis of the reception contract. If the multiprogram recording system is used, there is a possibility that the reception contract is not protected. Therefore, in the current IRD, a method of generally using the single program recording system is considered.
However, the multiprogram recording system has an advantage in that a plurality of programs can be simultaneously recorded. Further, when considering the realization of future multichannel scenarios, there is a high probability such that the multiprogram recording system will be used in an IRD in future.
If the IRD which supports the multiprogram recording as mentioned above is put on the market in the future, the recording medium recorded by the multiprogram recording system and the recording medium recorded by the single program recording system will both exist in the marketplace. There is, consequently, a possibility that the recording medium recorded by the multiprogram recording system is loaded into the recording/reproducing apparatus connected to the IRD which does not support with the multiprogram recording system via the IEEE1394 and is reproduced. If the transport stream of the multiprogram recording system is sent to the IRD which does not support the multiprogram recording system as mentioned above, it cannot be correctly reproduced and the user may become confused.
It is, therefore, an object of the invention to provide a receiving apparatus of a digital broadcast which can discriminate whether a reproduced transport stream is based on a multiprogram recording system or a single program recording system and can perform a proper process in accordance with a discrimination result about whether it is based on the multiprogram recording system or single program recording system.
According to the invention, when a transport stream of MPEG2 from a recording/reproducing apparatus is reproduced, whether the transmitted transport stream of MPEG2 is based on a single program recording system or a multiprogram recording system is discriminated in an IRD. In case of the transport stream of the multiprogram recording system, a video packet and an audio packet of a program of the smallest program number among a plurality of programs are extracted and decoded. In case of the transport stream of the multiprogram recording system, the transport stream is not decoded but a video image and audio sound can be further muted or a warning indicating that they cannot be reproduced can be displayed. Thus, even if a tape cassette recorded by the multiprogram recording system is loaded into a digital video cassette recording/reproducing apparatus and the transport stream of MPEG2 is inputted to the IRD which does not support the multiprogram recording system upon reproduction, the user is not confused.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.